The main whey protein in milk is β-lactoglobulin which has a molecular weight of around 36 kDa. Other important whey proteins in milk are α-lactalbumin with a molecular weight of around 14.5 kDa and bovine serum albumin with a molecular weight of around 69 kDa. There is a need for vegetable (i.e. edible plant) protein analogues of animal derived proteins and, in particular, milk proteins for both social and health reasons. However, the taste, mouth feel and nutritional properties of milk proteins are difficult to reproduce using vegetable protein.
Vegetable proteins are, nevertheless, used in a number of different applications, including both food and non-food applications
One vegetable protein which has been produced in a number of different forms, including both dried powder and liquid form, is soya protein. EP-A-1 512 328 discloses soluble soya protein and a method for producing such soluble soya protein using an enzyme, preferably a protease of fungal origin, to produce a material having high solubility and high anti-oxidant capacity without the normal bitterness and beany flavour associated with hydrolysed soy materials.
Other vegetable proteins useful because of cost, amino acid profile or other nutritional properties have, in practice, been more difficult to use, particularly in liquid form. Cereal proteins, for example wheat, are generally difficult to process because of the high proportion of insoluble and difficult to handle material. Cereal proteins would be particularly advantageous and products have, nevertheless, been developed using cereal proteins.
EP-A-0 672 352 relates to processes for the preparation of glutamine-rich peptides, in particular for use in food preparation. One of the particular glutamine-rich peptides disclosed in this document is based on wheat protein. However, the vegetable proteins, including the wheat proteins disclosed in EP-A-0 672 352, have extremely low molecular weights.
WO-A-2004/047549 discloses a process for preparing vegetable protein suspensions including wheat protein suspensions which are microbial stable without the addition of any preservatives and with a water activity of 0.4 to 0.9. These products have a wide range of degrees of hydrolysis which would result in varying molecular weight distribution.
A need exists for a composition comprising a vegetable protein which can be used as a milk protein replacement with generally similar properties, at least as regards solubility and average molecular weight to those of at least some of the milk proteins. In particular, it would be advantageous to provide a cereal protein having such properties.
The Applicants have surprisingly discovered that controlled separation of hydrolysed cereal proteins can provide a cereal protein with such beneficial properties and lead to a milk protein replacer for use in analogues of dairy products.